The announcement of Samsung’s new flagship Galaxy S6 smartphones has caused quite a stir, with a new design, interesting features, and a stripped back approach – but the company has lost what made its phones different in its war with Apple.

Samsung has been the dominant player in the smartphone market since it took the top spot in global smartphone shipments from Apple in 2011. The phone to help it do that was the Galaxy S2, Samsung’s first hit, which succeeded because it was both different and capable.

Part of what made the S2 great compared to competitors was the flexibility it gave the user. It had a removable battery, users could add more storage if they wanted – and it did this without compromising on the design.

But while Samsung has enjoyed success in volume across its entire range of smartphones, the Korean conglomerate has been locked in a war at the top with Apple and its iPhone. The Galaxy S line saw large growth over four years selling 200m before the introduction of the S5.

The original Galaxy S sold 25m units, the S2 40m, the S3 60m and the S4 sold 40m in the first six months heading towards 75m in total. But the Galaxy S5 didn’t live up to expectations, selling 40% fewer smartphones than expected – around 4m fewer than the S4 in its first three months on sale according to reports.

Samsung’s durable but cheap-feeling design and materials – mainly chromed and texturised plastics – had lost favour with consumers and critics alike compared to the premium metals and glass being used by Apple, HTC and others.

The Galaxy S6 has continued Samsung’s change in design language first introduced with the Galaxy Alpha, then the Galaxy Note 4, now pushed an extreme – all metal and glass.

Ben Wood (@benwood)

Samsung’s use of metal and glass addresses shortcomings of last year's all-plastic Galaxy S5 – good move. pic.twitter.com/PjKPHayM0k

Want more storage? Tough

The Galaxy S6 has no removable storage. That means what you buy is what you’re stuck with – 32GB, 64GB or 128GB of storage. That may seem a lot, but previous Samsung smartphones supported microSD cards, which were a cheap and effective way to add up to 128GB of storage and transfer that storage between devices.

Movies, TV shows, books, photos and music could be loaded onto the cards to keep the internal storage free for apps and then moved to a new device when needed. Instead the Galaxy S6 includes far more internal storage than its predecessors, but it has lost that flexibility to add more, which many people loved.

Part of that push has come from Google and its Android operating system. It’s Android 4.4 KitKat put heavy restrictions on the use of removable storage by apps, which made it behave differently to internal storage. However, Google’s latest Android 5 Lollipop relieved some of those restrictions making the SD card more useful again. Google’s own Nexus smartphones do not have removable storage, but that doesn’t mean others shouldn’t.

Battery be gone

Another Samsung favourite, the removable battery, has been sacrificed too. It’s something that has been lost across the wider smartphone industry as a whole, but Samsung was one of the last manufacturers to still include it, which made for an important differentiator.

You could argue that you don’t need a removable battery anymore, given that battery life is getting better and two or three days of useful life per charge is no longer unheard of, but that doesn’t help longevity.

Beyond being able to carry a spare battery to keep the phone running for longer, the removable battery allowed users to swap it out when it started to lose capacity – a problem plaguing all current mobile device batteries.

As the battery is discharged and recharged, the capacity diminishes. Most smartphones are charged at least three days a week. Modern battery technology has extended the useful life of a battery, but after two years of regular use batteries are not going to perform the same as new.

Replacing a battery that is not removable is not often possible by consumers, requiring a trip to a repair shop or risk damaging the phone while trying to take it apart, which is increasingly difficult.

Don’t get it wet

Rubber gaskets sealed the back of the Galaxy S5 to stop water getting into the delicate electronics, while a door on the USB port was needed. Photograph: Samuel Gibbs for the Guardian

The last thing Samsung has lost was the last to be introduced: waterproofing. The Galaxy S5 was waterproof to IP67 standards or 1m of fresh water for up to 30 minutes. It meant that a dunk in the toilet wasn’t an issue.

Waterproofing a smartphone has a cost to ease of use. The smartphone is only as waterproof as the seals protecting the sensitive electronic components, which means having fiddly doors on the charging ports most users will not be sad to see go.

User reaction to Samsung’s removal of these key features in pursuit of the design model so favoured by Apple has been mixed. Praise for the materials and premium look has been drowned out by negative reaction to missing components.

Without the ability to change the battery, the Galaxy loses the main point of having it. As to the astonished people who can't conceive of someone carrying a spare battery that always respond to this, just accept that some people have a bit of foresight.

Samsung seem to have been influenced by the reviewers who keep harping on about its phones being made of plastic, so they've gone down the "style over substance" route and put the phone in a shiny package while at the same time introducing two major downgrades (replaceable battery and Micro SD slot).

As someone who uses a phone because of its functionality, rather than as a fashion accessory or status symbol, this is a disappointment. I think I'll stick with my S4, which still works perfectly and hasn't been "dumbed down" like this new one.

Ha! Just as I was considering switching from an iphone to a Samsung because of the SD card memory capability. Maybe I'll end up with a HTC or LG after all...

Whether the negative reaction to feature removal will impact sales or whether Samsung’s bet on iPhone-like design will succeed is yet unknown.

“Samsung Galaxy S6 & S6 edge need to be winners in order to drive demand for Samsung’s entire portfolio,” said Ben Wood from research company CCS Insight.

Concluded Thomas Husson from Forrester: “Despite a new hardware design and some software innovation, there’s a risk Samsung’s 2015 flagship devices are insufficient for the company to regain brand leadership among consumers and businesses looking for high-end smartphone experiences.”